www/agate: Update 3.3.18 => 3.3.19

Changelogs:

• https://github.com/mbrubeck/agate/blob/master/CHANGELOG.md#3319---2025-09-18
• https://github.com/mbrubeck/agate/compare/v3.3.18...v3.3.19

Approved by: yuri@ (Mentor)

Differential Revision: https://reviews.freebsd.org/D52611